Chapter 18: Plastics, skin, and soft tissues. Flashcards
Skin: primarily cellular
Epidermis
Main cell type in epidermis; originate from basal layer; provide mechanical barrier
Keratinocytes
Neuroectodermal origin (neural crest cells); in basal cell layer of epidermis
Melanocytes
Have dendritic processes that transfer melanin to neighboring keratinocytes via melanosomes
Melanocytes
How do melanocytes differ among races?
Density of melanocytes is the same among races; difference is in melanin production
Skin: primarily structural proteins (collagen) for the epidermis
Dermis
- Acts as antigen-presenting cells (MHC Class II)
- Originate form bone marrow
- Have a role in contact hypersensitivity reactions (type 4)
Melanocytes
Sensory nerves: pressure
Pacinian corpuscles
Sensory nerves: warmth
Ruffini’s endings
Sensory nerves: cold
Krause’s end-bulbs
Sensory nerves: Meissner’s corpuscles
Tactile sense
Aqueous sweat (thermal regulation, usually hypotonic)
Eccrine sweat glands
Milky sweat
- highest concentration of glands in palms and soles
Apocrine sweat glands
What autonomic is in control of sweat production?
Most sweat is the result of sympathetic nervous system via acetylcholine
Drug type: increased skin absorption
Lipid-soluble drugs
Predominate collage type in skin; 70% of dermis; gives tensile strength
Type 1 Collagen
Resistance to stretching (collagen)
Tension
Ability to regain shape (branching proteins that can stretch to 2x normal length)
Elasticity
What causes Cushing’s striae?
Caused by loss of tensile strength and elasticity
MCC of pedicled or anastomosed free flap necrosis
Venous thrombosis
Flaps: what causes tissue expansion?
Occurs by local recruitment, thinning of the dermis and epidermis, mitosis
TRAM flaps: complications
Flap necrosis, ventral hernia, bleeding, infection, abdominal wall weakness
TRAM flaps: rely on what vessel?
Superior epigastric vessels
Most important determinant of TRAM flap viability?
Periumbilical perforators